Melbourne: World No 1 Serena Williams ruled out surgery to fix a persistent knee problem on Saturday as she declared herself "130 per cent fit" for the Australian Open.

USA's Serena Williams during a practice session in Melbourne on Saturday. Pic/AFP

The 21-time Grand Slam champion, gunning for a seventh title at Melbourne Park, retired due to soreness in her left knee during a singles match on January 6 at Hopman in Perth.